Hitherto, fly traps have been reused repeatedly, so that, even though they are emptied of the dead flies therein, they nevertheless usually contain eggs or maggots which subsequently hatch out, so that the repeatedly-used trap remains contaminated. Moreover, often a week elapses between successive garbage collections, during which period more maggots or eggs contained in the discarded contents of the trap hatch into more flies which escape to breed again. In the manufacture of my disposable fly trap disclosed and claimed in my previous U.S. Pat. No. 3,959,914 issued June 1, 1976 for Prefabricated Disposable Fly Trap, it was found that after cementing the screen to the border areas around the respective openings in the blank, surplus cement was exuded through the border portions of the screen mesh material and adhered to the machinery. The present invention successfully solves this problem.